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Wireless Communications and Mobile Computing
Volume 2017, Article ID 5396092, 10 pages
Research Article

Joint Design of Massive MIMO Precoder and Security Scheme for Multiuser Scenarios under Reciprocal Channel Conditions

1Instituto de Telecomunicações and DETI, University of Aveiro, Aveiro, Portugal
2Instituto de Telecomunicações, Department of Electrical and Computer Engineering, University of Coimbra, Coimbra, Portugal
3CISUC, Department of Informatics Engineering, University of Coimbra, Coimbra, Portugal

Correspondence should be addressed to Gustavo Anjos;

Received 25 August 2017; Revised 30 October 2017; Accepted 13 November 2017; Published 10 December 2017

Academic Editor: Daniele Pinchera

Copyright © 2017 Gustavo Anjos et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The exploration of the physical layer characteristics of the wireless channel is currently the object of intensive research in order to develop advanced secrecy schemes that can protect information against eavesdropping attacks. Following this line of work, in this manuscript we consider a massive MIMO system and jointly design the channel precoder and security scheme. By doing that we ensure that the precoding operation does not reduce the degree of secrecy provided by the security scheme. The fundamental working principle of the proposed technique is to apply selective random rotations in the transmitted signal at the antenna level in order to achieve a compromise between legitimate and eavesdropper channel capacities. These rotations use the phase of the reciprocal wireless channel as a common random source between the transmitter and the intended receiver. To assess the security performance, the proposed joint scheme is compared with a recently proposed approach for massive MIMO systems. The results show that, with the proposed joint design, the number of antenna elements does not influence the eavesdropper channel capacity, which is proved to be equal to zero, in contrast to previous approaches.